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Staphylococcus aureus was widely studied because it is capable of roducing heat – stable enterotoxin in the prepared food which is now popular in the general public (1). This study was designed to exprimentally survey the prepared foods in Khon Kaen, to identify the toxins therein and microorganisms in the nasal cavities and hands of the cooks, and to find their correlations. The informations to obtain would be beneficial for the prevention of staphylococcal food poisoning and the management aspect of epidemiology.
Our experimental studies on 193 prepaed food samples collected in Khon Kaen and on KKU campus revealed that the majority of samples contained 106 – 107 bacterial cells per gram of food. The staphylococci were 105 – 106 cells / gm. , S. aureus 103 – 104 cells/gm., and staphylococcus coagulase positve 102 – 104 cells/gm. of food.
The food samples containing the enterotoxinproducing S. aureus were such that the total bacteria, staphylococci, and S. aureus were quite high in number except the Staphylococcus coagulase positive vacteria where only 102 – 103 cells / gm. of food could be found the highest the enterotoxin – producing S.l aureus.
Four food samples were found to have entero toxins and staphylococcus coagulase postitive more than 105 cells / gm . of food (11.76% of enterotoxin producing S. aureus food samples or 2.07% of the total food samples)
We have found 97 food samples containing staphylococcus coagulase positive bacteria out of 193 (50.26%) . The food samples accommodating enterotoxin – producing S. aureus were 34 in number (17.62%). The most frequently found enterotoxin ypes were ABCD (25.64%) ; and A (23.08%), C(20.5%), ABD (15.31%), D,ACD (5.3%) , AD,BD(2,56%) were found in the less frequency in that order. The northeast of Thailand prepared foods (i,e. preserved raw pork – nam, papaya salad – tom, minced beff salad -- larb) were found to have predominated the number of positive samples. Twenty – eight out of 98 prepared food shops (28.57%) were found to be positive for the enterotoxin – producing S. aureus
The swab samples from 182 cooks indicated that the nasal cavity samples yielded 47.3% of the staphylococcus coagulate positive ; and there were 14.48% of them that produced the enterotoxin . The most prevalent toxin was type A (29.63%) . The hand swab samples showed 18.7% of the staphylococcus coagulate positive and 4.4% out of this produced enterotoxins. The enterotoxins A and ABCD were most frequently identified (25%). We have found no significant correlation of enterotoxins between the nasal cavity origin and the hand origin of the same cook. We can conclude form our experiment that the origin of this bacteria may be not from the cook, but rather from the raw material, from the environment while waiting for the buyers especially the food sample without the buyers especially the food sample without the lids, and while delivering from the kitchen the people involved.